Several circuits, many times called platforms due to their complex implementation of functions into a complex electronic building block, can be integrated into a circuit system, such as an embedded system, powered by a battery. These platforms may normally be developed with the intention of being the only platform in an embedded system. Therefore a platform normally has a standalone Power Management Integrated Circuit, PMIC, powered directly from a battery and powering all parts of the platform and handling the start up and shut down sequence of the power levels of the platform.
When more than one platform is integrated into an embedded system there can be two or more PMICs, each one powering the parts of its platform.
The platforms may communicate with each other through a communication bus controlled by software. One of the platforms may act as a power master and thereby is the first to start up, then starting up the other platform(s) and finally ordering the other platform(s) to shut down through a communication bus.
The approach of managing power through the communication bus may cause one or more issues, depending on the reason for shutting down. If the shut down is due to low battery and the power master shuts down first due to local settings in that platform, the other platforms may be left in undesired states. If the shut down is for saving power, the communication bus approach can be slow and/or power consuming such that less power is saved, and in worst case, the bus approach will not work at all if the power master shuts down too fast such that there is no time for software operated to shut down via the bus at all. Other issues may also occur due to compatibility issues between the platforms. It is therefore an object to provide an approach for power management that is less sensitive to such effects.